We are proposing a comprehensive research program to study the organization, turnover, and biogenesis of the proteins within the surface membrane of a rat hepatoma tissue culture cell (HTC). The proteins of the membrane will be characterized as to molecular size and location within the membrane. The turnover, synthesis and degradation of these proteins will be examined as a function of cell growth rate, and as a function of the proximity of individual polypeptides to each other within the membrane. The biogenesis and processing of selected membrane proteins will be followed to determine where in the cell these proteins are made, how they are processed, and how they get to their ultimate destination. The overall objective of this research is to utilize a variety of biochemical techniques to define the cellular mechanisms involved in the formation and maintenance of the limiting cell membrane. BIBLIOGRAPHIC REFERENCES: Tweto, J., Friedman, E., and Doyle, D. Proteins of the hepatoma tissue culture cell plasma membrane. In press J. Supramolecular Structure, Jan/Feb 1976. Tweto, J., and Doyle, D. Turnover of the plasma membrane proteins of hepatoma tissue culture cells. In press J. Biol. Chem., Feb 1976.